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1.
Fernando M. Lanas Janete H. Y. Vilegas Srgio Martins Elaine A. F. Gobato 《Journal of separation science》1994,17(4):237-244
An overview is presented of the analytical approaches developed by our research group over the last ten years for analysis of alternative fuel, both biomass and fossil. The alternative fuels are analyzed successively by PLC-8 (preparative liquid chromatography–group-type) fractionation and high resolution gas chromatography. Some of the possibilities for fractionation and characterization of alternative fuels are herein exemplified with sugar cane bagasse pyrolysis products. 相似文献
2.
Sannomiya M Rodrigues CM Coelho RG dos Santos LC Hiruma-Lima CA Souza Brito AR Vilegas W 《Journal of chromatography. A》2004,1035(1):47-51
The methanolic extract of the leaves of the medicinal plant Byrsonima crassa (Malpighiaceae) contain flavonoids with antioxidant activity. They were separated in a preparative scale using high-speed counter-current chromatography. The optimum solvent system used was composed of a mixture of ethyl acetate-n-propanol-water (140:8:80 (v/v/v)) and led to a successful separation between monoglucosilated flavonoids (quercetin-3-O-alpha-L-arabinoside, quercetin-3-O-beta-D-galactoside) and the biflavonoid amentoflavone in only 3.5 h. The purities of quercetin-3-O-alpha-L-arabinoside (95 mg), quercetin-3-O-beta-D-galactoside (16 mg) and the biflavonoid amentoflavone (114 mg) were all isolated at purity over 95%. Identification was performed by 1H NMR, 13C NMR and UV analyses. 相似文献
3.
A. L. M. Nasser L. P. Mazzolin C. A. Hiruma-Lima L. S. Santos M. N. Eberlin A. R. Monteiro de Souza Brito W. Vilegas 《Chromatographia》2006,64(11-12):695-699
The methanolic extract of the bark of the medicinal plant Qualea parviflora (Vochysiaceae) contains new nor-seco-triterpene and pentacyclic triterpenoids. They were separated in a preparative scale using droplet counter-current chromatography. The optimum solvent used was composed of a mixture of CHCl3/MeOH/H2O (43:37:20, v/v) in the descending mode and led to a successful separation of the new compound 28-nor-17, 22-seco-2α, 3β, 19, 22, 23-pentahydroxy-Δ12-oleanane, besides the known triterpenoids bellericagenin B, bellericaside B and arjunglucoside I . Identification was performed by ESI-MS, 1H NMR and 13C NMR analyses. 相似文献
4.
Godoi AF Vilegas W Godoi RH Van Vaeck L Van Grieken R 《Journal of chromatography. A》2004,1027(1-2):127-130
Turnera diffusa Willd. var. afrodisiaca (Ward) Urb. (syn. T. aphrodisiaca) belongs to the family of Turneraceae and is an aromatic plant growing wild in the subtropical regions of America and Africa. It is widely used in the traditional medicine as e.g. anti-cough, diuretic, and aphrodisiac agent. This work presents a 3 min chromatographic analysis using low-pressure (LP) gas chromatography (GC)-ion-trap (IT) mass spectrometry (MS). The combination of a deactivated 0.6 m x 0.10 mm i.d., restrictor with a wide-bore CP-Wax 52 capillary column (10 m x 0.53 mm i.d., 1 microm) reduces the analysis time by a factor of 3-7 in comparison to the use of a conventional narrow bore column. Chromatographic conditions have been optimized to achieve the fastest separation with the highest signal/noise ratio in MS detection. These results allow fast and reliable quality control of the essential oil to be achieved. 相似文献
5.
Luiz A. F. Coelho Jos V. Oliveira Saul G. D'vila Janete H. Y. Vilegas Fernando M. Lanas 《Journal of separation science》1997,20(8):431-436
The effects of temperature and solvent density on the characteristics of the extracts obtained from supercritical fluid extraction (SFE) of the volatile compounds from Brazilian rosemary (Rosamarinus officianalis L., Labiatae) using carbon dioxide (CO2) as solvent were investigated. The experiments were performed in a semi-batch laboratory scale home-made unit at two temperatures, viz. 310.15 and 320.15 K, over the pressure range of 100-160 bar. This study allowed to determine the crossover point and the maximum solubility of the oil. The products were analyzed by HRGC-MS, and compounds grouped in three different classes according to their molecular mass distribution in order to evaluate the influence of the variables studied on the characteristics of the extracts. The model proposed by Sovová was adopted in an attempt to interpret the mass transfer phenomena in the extraction process. 相似文献
6.
Fontana José D. Almeida Eduardo R. A. Baron Madalena Guimaraes Manoel F. Deschamps Francisco C. Schwartsmann Gllberto Cervi Armando C. Zanette Flávio Vilegas Janete LanÇas Fernando M. 《Applied biochemistry and biotechnology》1994,(1):295-313
The acetogenins are strongly bioactive natural compounds present in the bark, roots, leaves, and seeds of manyAnnonaceae plants. They are modified fatty acids and their cytotoxicities have been determined for different biological models including
the in vitro growth inhibition of several human cancer cell lines.
Very low acetogenin yield (< 0.1 g%) has been found previously in native phytobiomass, and we have now investigated the nonpredatory
exploitation of the seeds as acetogenin sources characterizing the seed triacylglycerols (dominant fraction; > 90% of the
whole lipid extracts) as potential valuable by-products. 相似文献
7.
8.
The anti-allergic active fractionation of hexane extracts of the leaves and stems of Anchietia salutaris var. martiana (family Violaceae) was performed by monitoring their activities with an in vitro bioassay system measuring the inhibitory effects on induced histamine release from guinea pig lung cells. Three known pentacyclic triterpenes (friedelin, alpha-amyrin, beta-amyrin) were isolated, but these compounds were inactive. Aliphatic hydrocarbons and methyl esters of fatty acids (palmitic, oleic, linoleic, linolenic acids) were detected in active fractions. All compounds isolated were detected for the first time in this medicinal plant. 相似文献
9.
The mutagenicity of ten flavonoids was assayed by the Ames test, in Salmonella typhimurium strains TA98, TA100 and TA102, with the aim of establishing hydroxylation pattern-mutagenicity relationship profiles. The compounds assessed were: quercetin, kaempferol, luteolin, fisetin, chrysin, galangin, flavone, 3-hydroxyflavone, 5-hydroxyflavone and 7-hydroxyflavone. In the Ames assay, quercetin acted directly and its mutagenicity increased with metabolic activation. In the presence of S9 mix, kaempferol and galangin were mutagenic in the TA98 strain and kaempferol showed signs of mutagenicity in the other strains. The absence of hydroxyl groups, as in flavone, only signs of mutagenicity were shown in strain TA102, after metabolization and, among monohydroxylated flavones (3-hydroxyflavone, 5-hydroxyflavone and 7-hydroxyflavone), the presence of hydroxyl groups only resulted in minor changes. Luteolin and fisetin also showed signs of mutagenicity in strain TA102. Finally, chrysin, which has only two hydroxy groups, at the 5-OH and 7-OH positions, also did not induce mutagenic activity in any of the bacterial strains used, under either activation condition. All the flavonoids were tested at concentrations varying from 2.6 to 30.7 nmol/plate for galangin and 12.1 to 225.0 nmol/plate for other flavonoids. In light of the above, it is necessary to clarify the conditions and the mechanisms that mediate the biological effects of flavonoids before treating them as therapeutical agents, since some compounds can be biotransformed into more genotoxic products; as is the case for galangin, kaempferol and quercetin. 相似文献
10.
L. C. Santos M. Dachtler F. D. P. Andrade K. Albert W. Vilegas 《Analytical and bioanalytical chemistry》2000,368(5):540-542
The on-line separation and identification of two important taxonomic markers for plant species of the Paepalanthus genus, the flavonoids 6-methoxykaempferol-3-O-β-D-glucopyranoside and 6-methoxykaempferol-3-O-β-D-6″(p-coumaroyl)glucopyranoside,
has been performed with an HPLC-NMR coupling using C30 phase. 1D spectra have been recorded in the stopped-flow mode for the two predominant chromatographic peaks. This is the
first application of HPLC-NMR coupling using C30 phase to a taxonomic problem. The technique drastically reduces the required amount of sampling for structure determination.
Received: 20 March 2000 / Revised: 14 June 2000 / /Accepted: 23 June 2000 相似文献